Previous homeowner was victim of watching too many DIY reality shows, nothing has been done correctly or works like it should. If this IS correct, then I will eat crow.

Tall pipe on the left is where the washing machine drains into. There is a utility sink on the right side fitting. No venting. I don't know if the 2" running up the wall runs to a main vent, if it is its own vent, or if it's used as a drain from something upstairs. I will check and find out.

When the washer drains, the sink fills up near to the top. I don't know if I have an obstruction or if it's due to lack of vent; or a combination of both. I'm going to try and clean everything out just in case.

I'm doing a small remodel on this laundry room (mainly just painting the concrete walls, replacing the sink, installing a cheap floor...ripped out black-molded carpet that was used in the laundry room...WTH???)

Left supply lines are for the washer. Right is for the sink.

Old drain. Won't work with the new sink. Old sink was raised 1" off the floor just so they had clearance.

Thinking the drain T needs to be moved to the right a bit, and then done correctly, with the correct fitting.

I turned on the upstairs sink, and it's draining down the pipe labeled below. The pipe that the washing machine is draining into is the one that's a couple feet closer to us.

In this picture, you see the drain pipe for the upstairs sink on the left. The pipe on the right is the one that's hooked to the laundry machine drain. I would ASSume that this is also the vent for the sink? I looked in the attic, and there is a pipe coming up in this same area tied over into another pipe (vent) going up through the roof. This leads me to believe this pipe is purely vent (no drain coming from above).

With that said, what is the proper way to set up the washer and sink traps/vents? Thank you!

is there a bathroom above the kitchen on a 2nd floor? if not, then most likely this is a properly vented system. if there is, you likely have a lav/tub draining down through this line and you have a wet vent on your laundry. this is not ideal or legal, but does give some venting as opposed to none.

have you opened up that cleanout wye and snaked out the drain? this sounds like a clogged up underground, and thankfully you were left with a cleanout, albeit an awkwardly placed one, that you can use. you'll want to rent a good sized power snake for this, as these lines can go a long way and those old cast iron lines tend to get all corroded and need a little power to break through some of the gunk.

As for the trap, its not horrible, but you'll want to cut off the elbow on the sink trap and glue on an adapter and fit a standard P trap to the sink. This should give you the side to side flexibility to get it to line up properly to the sink. a new tailpiece wouldn't hurt either, with all plastic parts rather than that mix and match of plastic and metal.

it looks like you're darn near level on that drain line from the washer to the drain, you might want to lift it up and resupport it about an inch or so higher to get proper fall.

At HD now, mobile.
Nothing above the kitchen. Haven't snaked yet, but am buying one.
No ABS here I can see. Think I am going to cut it all off, couple a Fernco to the stub, and redo it in PVC.
...I'll check back in a bit, low batt.

I'm not entirely sure what you mean...I was going to have the sink and washer on the same drain line. Please forgive me, I don't know all the terminology.

Also, I did not see black ABS at Home Depot. Should I look elsewhere and use all ABS? Or, should I redo it in PVC, with a Fernco type rubber connector near the waste stack connecting the ABS to new PVC? That still leaves me needing something up top. Unless I used a PVC Sanitary-T with 2x PVC "stubs" sticking out up/down, with a Fernco rubber connector on each end of it.

Please forgive my hack-up Visio job here (feel free to draw on it!). I thought this was the solution you are suggesting, but looking closer at your post, I don't think it is.

I was going off of the popular diagram that Terry uses on this site. Is it incorrect?

Click to expand...

A sanitary tee can only be placed on it's back for a dry vent take-off, never a drain attachment. Terry's fitting is a combo, which is the equivalent of a wye and 1/8 bend.
Terry's is correct in this regard.

Are you using a different horizontal pipe for each drain into the main stack on the right? Problem is, if the horizontal drain pipe is any higher, it will be at or above the level of the sink drain, see here:

A sanitary tee can only be placed on it's back for a dry vent take-off, never a drain attachment. Terry's fitting is a combo, which is the equivalent of a wye and 1/8 bend.
Terry's is correct in this regard.

Click to expand...

I misunderstood dlarrivee's post about being on it's side, I thought that meant side as in the vertical pipe. I was thinking of the bottom one as more 'on its back', but nevertheless, I would still be in the wrong!

Must be a pretty common mistake that people make huh...I'm looking at that guide that Terry posted above.